taxonomy-mirrored-posts.php

<?php
/*
Plugin Name: Taxonomy Mirrored Posts
Description: Enables PHP/Theme Developers to register post types that will use Taxonomy Terms to Mirror Posts.
Version: 0.1
Author: Mike Schinkel
Author URI: http://mikeschinkel.com
*/
/*
 * TODD: Need to delete _mirrored_term_id when a post is deleted.
 * TODD: Need to delete term when post is deleted (or maybe not?)
 * TODD: Need to disallow deletion of non-orphaned terms.
 */

if (!class_exists('TMP_Hooks')) {
	class TMP_Hooks {
		function __construct($args=array()) {
			$this->TMP_Hooks($args);
		}
		function TMP_Hooks($args=array()) {
		}
		static function on_load() {
			add_action('save_post', array(__CLASS__,'save_post'),10,2);
			add_action('init',array(__CLASS__,'init'));
		}
		static function init() {
			do_action('register_taxonomy_mirrored_post_types');
		}
		static function save_post($post_id, $post) {
			$mirrored_post_types = array_keys(get_taxonomy_mirrored_post_types());
			if (in_array($post->post_type,$mirrored_post_types)) {
				$post_type_object = get_post_type_object($post->post_type);
				if (strlen(trim($post->post_title))==0) { // This happens during auto-draft, maybe other times.
					if (!in_array($post->post_status,array('auto-draft','trash','hidden'))) {  // Trap this to gain insight; insight helps us make it more robust.
						$mirrored_post_types = implode(' or ',$mirrored_post_types);
						echo "ERROR: Unexpected during insert of either $mirrored_post_types post types:\n<br/>";
						echo "post_status: $post->post_status\n<br/>";
						echo "post_title: $post->post_title\n<br/>";
						echo "post_name: $post->post_name\n<br/>";
						exit;
					}
				} else if ($post->post_status!='auto-draft') {
					$mirrored_id = get_mirrored_post_term_id($post_id);
					$type_name = strtolower($post_type_object->labels->singular_name);
					$updated_term = array(
						'name' => $post->post_title,
						'description' => "Mirrored taxonomy term for $type_name {$post->post_title}",
						'slug' => (is_numeric($post->post_name) ? sanitize_title_with_dashes($post->post_title) : $post->post_name),
					);
					$term = get_term($mirrored_id,$post->post_type,ARRAY_A);
					if (is_wp_error($term)) {
						$term = get_term_by('name',$post->post_title,$post->post_type);
					}
					if (is_wp_error($term)) {
						echo 'ERROR: We should not get a WP_Error here. If it does need to validate assumptions.';
						print_r($term);
						die();
					}
					//print_r($term);  TODO: Need to deal with duplicate slugs
					if (is_array($term) || is_object($term)) { // Not sure if the object test is needed, but just in case
						$updated_term = array_merge((array)$term,$updated_term);
						//$updated_term[$term_id] = $mirrored_id;
						$new_term = wp_update_term($updated_term['term_id'],$post->post_type,$updated_term);
						if (is_wp_error($new_term) && isset($new_term->errors['duplicate_term_slug'])) {
							//TODO: Fixed duplicated terms
						}
					} else {
						$new_term = wp_insert_term($post->post_title,$post->post_type,$updated_term);
					}
					if (is_wp_error($new_term)) {
						header('Content-type:text/plain');
						echo 'ERROR: We should not get a WP_Error here. If it does we need to validate our assumptions.';
						print_r($new_term);
						die();
					}
					update_mirrored_post_term_id($post_id,$new_term['term_id']);
				}
			}
		}
	}
}
TMP_Hooks::on_load();

global $tmp_taxonomy_mirrored_post_types;
$tmp_taxonomy_mirrored_post_types = array();

function register_taxonomy_mirrored_post_type($post_type) {
	global $tmp_taxonomy_mirrored_post_types;
	$tmp_taxonomy_mirrored_post_types[$post_type] = array(
		'post_type' => $post_type,
	);
}
function get_taxonomy_mirrored_post_types() {
	global $tmp_taxonomy_mirrored_post_types;
	return $tmp_taxonomy_mirrored_post_types;
}
function is_post_type_mirrored($post_type) {
	global $tmp_taxonomy_mirrored_post_types;
	return isset($tmp_taxonomy_mirrored_post_types[$post_type]);
}
function get_mirrored_post_term_id($post_id) {
	return (int)get_post_meta($post_id,'_mirrored_term_id',true);
}
function update_mirrored_post_term_id($post_id,$value) {
	update_post_meta($post_id,'_mirrored_term_id',$value);
}
function get_mirrored_post_id($term_id) {
	global $wpdb;
	$sql = $wpdb->prepare("SELECT post_id FROM {$wpdb->postmeta} WHERE meta_key='_mirrored_term_id' AND meta_value=%d",$term_id);
	$post_id = (int)$wpdb->get_var($sql);
	return $post_id;
}
function get_taxonomy_mirrored_post( $taxonomy_term ) {
	static $taxonomy_posts;
	if (!isset($taxonomy_posts)) {
		$taxonomy_posts = array();    // TODO: Optimize in case the query returns large data set
		$result = new WP_Query("post_type={$taxonomy_term->taxonomy}&posts_per_page=-1");
		foreach($result->posts as $post) {
			$term_id = get_mirrored_post_term_id($post->ID);
			$taxonomy_posts[$term_id] = $post;
		}
	}
	return (isset($taxonomy_posts[$taxonomy_term->term_id]) ?	$taxonomy_posts[$taxonomy_term->term_id] : false);
}
function get_post_taxonomy_mirrored_posts($post,$taxonomy) {
	if (is_numeric($post))
		$post = get_post($post);
	$terms = wp_get_post_terms($post->ID,$taxonomy);
	$term_ids = array();
	foreach($terms as $term)
		$term_ids[] = $term->term_id;
	$term_ids = implode(',',$term_ids);
	global $wpdb;
	$sql = $wpdb->prepare("SELECT post_id FROM wp_postmeta WHERE meta_key='_mirrored_term_id' AND meta_value IN ($term_ids)");
	$post_ids = array();
	$posts = $wpdb->get_results($sql);
	foreach($posts as $post)
		$post_ids[] = $post->post_id;
	$post_ids = implode(',',$post_ids);
	$posts = get_posts("post_type=$taxonomy&numberposts=-1&include=$post_ids");
	return $posts;
}